This invention relates to a catheter apparatus, more particularly to an underfluid ultrasound parametric imaging catheter apparatus.
Medical Ultrasound
In the field of medical ultrasound, one acquires ever more knowledge of reality by solving problems and finding better explanations. Medical ultrasound over the past 25 years has evolved to become one of the most commonly performed imaging and hemodynamic examinations. Modem ultrasound machines can replicate those features previously obtained by more invasive means such as, cardiac catheterization. Those features attributable to invasive technologies at least include: 1) ability to obtain anatomic images, 2) ability to quantitatively assess function, 3) ability to measure hemodynamics, and 4) ability to visualize blood flow (i.e., an angiographic substitute). The advantages of using ultrasound technology include: 1) non-invasive, 2) no ionizing radiation (a safe repeatable energy source), 3) comparatively low cost, 4) obtaining hemodynamics as well as images, 5) technology capable of being fabricated into different sizes and shapes (e.g., ultrasound tipped catheter), 6) rapid temporal and spatial resolution, and 7) portable, etc.
Computer Interface
With the incorporation of more sophisticated computer interfacing, in the later part of the twentieth century, diagnostic ultrasound has entered into the era of information acquisition. The prerequisites for this change include use of newer sophisticated information acquisition and management techniques, reconstruction or assimilation of multiple forms of information, segmentation of the pertinent or most meaningful information, quantitation and display of the result. The acquired information represents the physiology and structure of the insonated environment (i.e., tissue, muscle, blood, etc.). Information acquisition techniques include new Doppler technology, such as tissue Doppler imaging (TDI) and strain-rate imaging (SRI), harmonic imaging, pulse-inversion imaging, and pulsed and intermittent imaging, etc.
Ultrasound Catheter
A recent innovation in diagnostic medical ultrasound is the development and introduction of invasive ultrasound tipped catheters including (U.S. Pat. Nos. 5,325,860, 5,345,940 and 5,713,363 issued to Seward et al.). These catheters allow one to obtain high-resolution images from within the confines of fluid filled spaces (i.e., heart, urinary bladder, blood vessels, etc.). However, these newest catheters have the capacity not only to obtain an image but in addition also to obtain more unique physiologic ultrasound information which to date has not been feasible using a rotating ultrasound element catheter. For example, full Doppler capabilities are now possible with the ultrasound catheter and include pulsed and continuous wave Doppler, color flow Doppler, tissue Doppler, etc. Newer evolving acquisition technologies include pulse inversion, harmonic imaging, strain-rate imaging, intermittent imaging, etc.
New Image Paradigm
Information can be fractionated into its small individual digital components, each unit is xe2x80x9cparameterizedxe2x80x9d (i.e., has quantifiable value), and groups of related units can be expressed as a volumetric image. Parametric imaging referred herein is the term applied to the acquisition of various types of quantifiable events and in the case of ultrasound represents the display surrogates information representing anatomic, functional, hemodynamic, or physiologic events. A parameter is defined as a mathematical quantity or constant whose value varies with the circumstances. Examples include blood pressure, pulse rate, and an infinite number of other visible and non-visible events which permeate our reality. The quantifiable event can be measured and expressed as a change over time, for example a change in pressure over time, is most often graphed or charted as a graph (e.g. a pressure curve) with the magnitude of pressure on the ordinate and time on the abscissa. However, today a sophisticated imaging device can record such events throughout a field or volume of interest (i.e., a volumetric two- or three-dimensional image of the spatial distribution of the event). Fields of specific individual or group events can then be displayed as a geometric image as opposed to a graphic or one-dimensional display of a single continuous happening. The analogy is being capable of simultaneously measuring numerous similar or dissimilar individual events and instead of graphing the result, displaying the phenomena as a dynamic geometric image (instead of looking at a single bee in a hive, the action of the whole hive is assessed simultaneously).
The observed events can occur in a regular or irregular manner, distribute in a predictable or unpredictable manner, or remain constant or change randomly, etc. The events are virtually always continuous or cyclical (repetitive) but can be broken down into smaller and smaller components, which can be looked upon as quanta (i.e., elemental units) and displayed in a computer presentation as quantifiable pixels. It is the elemental unit(s), which can be pictured as changing over time (i.e., time and magnitude, such as pressure or temperature). However, the whole field of units (quanta) is best presented as a distribution of measurable units dispersed throughout a defined spatial domain (for example, the distribution of pressure throughout a cavity of the heart or temperature of the body). A parametric imager enables the presentation of quantifiable, information as a geometric picture of a continuous event. The event becomes the image while the fundamental image or source information becomes subservient or nonessential. At any moment in a temporal sequence, the event can be captured as a volume with a specific quantifiable distribution. However, when it is viewed over time, the event is displayed as a moving surface, and or volume (i.e., a two-, three-, fourth-dimensional or higher-dimensional image). Event information may include point of initiation (epicenter: for example, a very hot infected ear causing an increase in body temperature), distribution (epicenter spreading outward), moment to moment change (evolution or wave front distribution), decay (transient, periodicity, etc.), and others. In topological language, the point is called a repeller and the expanding phenomenon an attractor. An attractor, in general, is a region of space that xe2x80x9cattractsxe2x80x9d all nearby points as time passes. To the human senses, the imaged event may be a normally visible phenomenon such as the contracting wall of the heart, or a non-visible phenomenon (referred to as higher-dimensional events) such as the distribution of electricity, or in the case of ultrasound electricity can be pictured through a display of a parametric surrogate. The manipulation and display of data are solved by quantum mathematical concepts. The parametric image is a geometric image of a quantifiable phenomenon but not a mere picture of that phenomenon (for example: the motion of muscle contraction is visible, however, a parametric surrogate of contraction would be the display of change itself). The parametric image often does not appear similar to the fundamental event.
Quantum Mathematics Concept
Generally, all physical processes are quantum-mechanical. The quantum theory of computation is an integral part of the fundamental understanding of reality. Quantum solutions applied to information, displayed as a geometric image, provide a revolutionary mode of explanation of physical reality. The human does not accord equal significance to all our sensory impressions but is known to perceive reality best when presented as an image. Thus, given the fact that general theories about nature are best expressed in quantifiable mathematical form and that geometric images are the most mature expression of a mathematical computation, it is logical that a parametric image solution will have considerable acceptance as a pleasing as well as quantifiable diagnostic imaging solution. As the trend towards faster, more compact sophisticated computer hardware continues, the technology must become even more xe2x80x9cquantum-mechanicalxe2x80x9d, simply because quantum-mechanical effects dominate in all sufficiently small systems. The digital pixel of an image becomes a quantifiable unit (i.e., quanta) belonging to a family of events having related or meaningful characteristics. The repertoire of computations available to all existing computers is essentially the same. They differ only in their speed, memory capacity, and input-output devices. However, a xe2x80x9cquantum computerxe2x80x9d is a machine that uses uniquely quantum-mechanical effects, especially interference, to perform wholly new types of computation that would be impossible on earlier generations of computers. Such computational mathematics is a distinctively new way of looking and assessing nature. In the twentieth century, information was added to the evolution of modem computers, which has allowed complex information processing to be performed outside the human brain. As one enters into the twenty-first century, quantum computation is slowly being introduced which is the next step in the evolution of information presentation. Observations of ever smaller, subtler effects are driving ever more momentous conclusions about the nature of reality. Ever better explanations and predictions can successively approximate visible or non-visible events, which permeate the reality.
Physiological events can be computed as distributions of quanta (i.e., pixels of measurable information). Today, computers can provide integrated quantitative answers to certain otherwise unseen or unappreciated events. Quantum events are initially given a position and then xe2x80x9cspread outxe2x80x9d in a random volumetric distribution. Because of the unpredictability of the volumetric event, increasing computational resources must be used to measure and present the information. Quantum solutions are often used to make probabilistic predictions, however, many of the predictions can be used to predict a single, definite outcome (example: a geometric image of electricity or its surrogate, as described herein, can be used to very accurately localize the anatomic site of an electrical excitation of the heart muscle). Quantum solutions of complexity show that there is a lot more happening in the quantum-mechanical environment than that literally meets the eye. Quantum phenomena can be highly predictable and can foster the increasing use of computational solutions for the assessment of physiologic events.
Accordingly, there is a need for a computer driven acquisition device to acquire quantifiable events from today""s state-of-the-art medical ultrasound machines, such as the ultrasound empowered catheter system as described herein, to rapidly acquire physiologic information and provide images of continuously changing volumetric (spatial) information.
To overcome the natural limitations in the art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention provides a catheter apparatus for parametric imaging a visible fourth-dimensional or a non-visible higher-dimensional events in an underfluid environment.
Why a catheterxe2x80x94The present invention pertains to an ultrasound tipped catheter; however, the imaging solution described in the present invention could apply to any complex computer manipulation of acquired information. The ultrasound tip catheter described in the present invention has not accommodated a parametric solution before. The ultrasound catheters in the present invention are those capable of rapidly acquiring finite information presented as quantifiable pixels. The acquisition elements are in multiples aligned and spaced in a manner to act in concert to obtain a field of information (i.e., a symphony of events). Capable ultrasound include linear array, curved array, vector phased array, phased array, and multi-dimensional arrays. All of these ultrasound transducers are characterized by having multiple piezoelectric elements lying closely together and function to insonate a field and acquire underlying information. The resulting image can be a flat two-dimensional tomogram or a volumetric three-dimensional image.
Why ultrasoundxe2x80x94Ultrasound imaging has to date received no appreciable parametric application. Digital solutions have been slow to evolve in ultrasound imagery, as opposed to other image solutions such as radioisotopes, X-ray, or magnetic resonance. The ultrasound catheter of the present invention is unique and without comparable technology. The unique image solution of the present invention is thus applied to an equally unique acquisition device (the catheter).
What is parametric imaging and why there is potential for confusionxe2x80x94The term xe2x80x9cparametric imagingxe2x80x9d has been used for years to apply to the general concept of using measurable information to form an image. In this general definition, one could say that any picture which has a numerical value to its contents is parametric (i.e., its component parts are parameterized). This can be further extrapolated to say that any picture which is digital, such as computerized tomography (CT), magnetic resonance (MR), isotope scans, Doppler ultrasound, etc., is parametric because some or all of the acquired information is expressed as a measurable number. The present invention herein addresses a unique parametric image solution and one that requires a higher order computer solution and is not merely displayed of pixelated digital information.
Firstly, the whole image is broken down into its smallest quantifiable components (i.e., pixels, quanta, etc.). Currently, this exists for CT, MR, isotopes, and Doppler but does not exist for the remainder of the ultrasound image, x-rays, etc., which is typically presented as analog pictures.
Secondly, the digital components (i.e., pixels) are parameterized and measurable, a feature, which exists with CT, MR, and isotope images but has only recently been possible with experimental ultrasound Doppler. The analog components of images have been xe2x80x9cdigitizedxe2x80x9d in an attempt to overcome this second requirement, however xe2x80x9cdigitizationxe2x80x9d significantly narrows the measurable features. There are numerous historical examples of digital or digitized information pictures, which can be called parametric. However, this is not sufficient for the present invention herein.
Thirdly, and most importantly for the present invention, the parameterized pixels are recognized by the computer as having unique quantifiable features. Each pixel has a unique identifiable quantity. Pixels with similar features are classified as families, distributions, or probabilities. Lastly, the classified pixel features are themselves presented as a geometric picture (i.e., the Parametric Image Solution pertaining to the present invention). xe2x80x9cParaxe2x80x9d refers to a substitute or replacement of reality; xe2x80x9cmetricxe2x80x9d refers to mathematical, quantifiable; and xe2x80x9cimagexe2x80x9d refers to a geometric picture (of a mathematically derived surrogate of reality). The resultant picture may have little similarity to the image described in the second requirement. A new parametric image is formed which itself is a picture of selected information. The selected information is normally imbedded within a fundamental image. Such a process occurs rapidly to be clinically applied. Very sophisticated computer solutions are required to handle these very large digital solutions and carry out the statistical sorting of pixel features. Such parametric solutions currently exist in some CT, MR and isotope imaging but are essentially experimental. There is no mention of this form of parametric solutions in ultrasound imagery. There is absolutely no mention of such solutions applied to an underfluid ultrasound catheter.
What makes the present invention uniquexe2x80x94Nature and its physiologic underpinnings are complex. Complex phenomena continuously change in a linear or cyclical manner. Breaking such events down into small components and then expressing complexity as understandable geometric images are extremely informative. Such images impart new information. Most importantly, such information solutions are very reproducible, more accurate than conventional measuring tools, and are quantifiable. Important prerequisites include objectivity, reproducibility, quantitation, and multidimensional display. Although a historically familiar term, parametric image, is used, the concept disclosed is a new paradigm. The solution described herein is completely new and has never been applied to an underfluid ultrasound imaging system. Nor does the solution of the present invention have any intuitive counterpart in existing ultrasound or even in related comparable xe2x80x9cimagingxe2x80x9d modalities such as magnetic resonance, computerized tomography, or isotopes.
The present invention provides an imaging catheter apparatus having an acquisition device or parametric imager to interpret and present to the user a new geometric image of a selected parameter of an event acquired from an ultrasound imaging catheter apparatus. The selected parameter of an event which can be a visible fourth-dimension or non-visible higher-dimensional event is displayed in an image format which distinct from the conventional fundamental ultrasound image.
In one embodiment of the present invention, an ultrasound-based parametric imaging catheter apparatus adapted for an underfluid environment is described by way of example. Accordingly, parametric imaging is defined hereinwith in terms of a unique ultrasound image presentation and quantitation technique. Without the parametric solution, described herein, information parameters appear imbedded in the fundamental image display having no separable or unique image. With the described parametric solution, quantifiable parameters such as computed velocity, surrogate electrical phenomena, derived pressure, or other constantly changing events are separated and presented as new unique images which are more readily perceived and understood by a user. Most importantly, they are objective, reproducible, quantitative (mathematical) and multidimensional. Accordingly, an underfluid ultrasound parametric imaging catheter apparatus of the present invention is capable of visualizing quantitative physiology and altered physiological states of insonated surroundings. The parametric image is one of phenomena which are normally too fast, too slow, or too complex to be accommodated with current imaging solutions.
One embodiment of the underfluid ultrasound imaging catheter apparatus in accordance with the principles of the present invention includes: a catheter body; a transducer, disposed on the catheter body, transmitting signals to a structure proximate the transducer outside of the catheter body and receiving signals which represent an event of at least one selected parameter; a parametric image processor processing and imaging at least one selected parameter of the event. The event can be a four-dimensional event visible to a human user""s eye or a higher than four-dimensional event normally non-visible to the human user""s eye.
Dimensions: The subject of dimensions is complex and often confusing. Three dimensions totally explain our spatial reality, which encompass height, length and width. A volumetric image, which contains three spatial dimensions, is conventionally called a three-dimensional or volumetric image. Visible motion, as described by Einstein in 1908, is designated the fourth dimension of our reality. A volumetric image, which visibly moves, is called a four-dimensional image. Our reality is, however, permeated with an infinite number of normally non-visible moving events (the term higher-dimensional phenomenon has been applied to non-visible events, which permeate our reality but should not be confused with theoretical physicsxe2x80x2 use of the same descriptor, which refers to parallel universes or dimensions). Examples of non-visible phenomena include heat, electricity, transformation, etc. We normally perceive these events as continuous, for example, the changing temperature of the body. The non-visible events are perceived as complex, unpredictable linear or cyclical variables. In physics, complex natural events have been discussed under the headings of chaos, fractals, fuzzy logic, quantum mechanics, etc. All of these disciplines are based on the fact that immense predictability of complex systems can be obtained from less than absolute solutions. By breaking a complex event into quantifiable (i.e., parameterized) components and then presenting the event as a probability distribution in an image format is extremely enlightening. The parametric image described herein presents visible and non-visible events as geometric pictures, thus brings an otherwise complex event into our visible reality. The technique requires sophisticated computer management of information which results in extremely reproducible, quantifiable information.
Other embodiments of an underfluid ultrasound imaging catheter apparatus in accordance with the principles of the invention may include alternative or optional additional aspects. One such aspect of the present invention is that the transducer is an ultrasound-based transducer. The transducer is the catheter component which acquires information. The configuration of the transducer can be in a variety of formats. The ultrasound transducer configuration (format) can be of any form that can be accommodated into a catheter as described herein and acquire paramaterized information in a two-, three-, four-, or a higher dimensional image presentation. For example, the transducer can be a group of transducer elements or an array of transducer elements. Also, the type or operation type of the ultrasound-based transducer can be in a variety of formats. For example, the transducer can be an offset stereoscopic imaging ultrasound transducer array, a sector array, a linear array, a linear phase array, a phase linear array, a curved phase array, vector array, etc.
Another aspect of the present invention is that the selected quantifiable parameter is truly an ultrasound surrogate of a parametric phenomenon. Events such as blood flow velocity, perfusion, pressure, contractility, image features, electricity, metabolism, transformation, and a vast number of other constantly changing parameters are brought into the realm of visual reality. However, the event itself (i.e., electricity) is not visualized. Instead, ultrasound produces a surrogate parameter which can accurately predict an event such as electrical depolarization/repolarization.
Parametrics is an old term, however, in the context described herein, the application is totally different. Historically, a digital imaging system such as magnetic resonance, nuclear radioisotopes, x-ray, and computed tomography have been used to acquire pixelated information. Ultrasound has not accommodated digital solutions and in particular use of an underfluid imaging catheter is unique. The term parametric imaging has been applied in various manners but not to the ultrasound solution. The unique aspect of the present invention is the extraction of parametric information from the fundamental image and reformatting this new information into a new geometric image (i.e., parametric image).
In one aspect of the present invention, the invention is unique in that it is an underfluid catheter system with the creation of a new geometric parametric event imager.
Using an underfluid ultrasound catheter apparatus and the concept of quantum computation, one can describe families of physiologic events by geometrically expressing surrogate features. This presentation assists in explaining such events, and ultimately describing why something happens by invoking the flow of time. Quantum descriptions of distributions resolve events into measurable units of simplicity and comprehensibility and can be looked upon a high-level simplicity derived from low-level complexity. The surrogates of physiologic phenomena can be displayed as easily understood geometric images suited to the human""s four-dimensional comprehension of reality.
Accordingly, the present invention provides a geometric image for an objective result of an event. Such event is reproducible. One obtains the same result each and every time if provided comparable parameters. The present invention provides a capability of placing a numerical result into a measurable scheme. Further, the present invention has a capacity to expand as a spatial distribution in surface, area, and volume.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objectives obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.